1. Field of the Invention
The present invention relates to a screen printing apparatus and a screen printing method for printing a soldering paste with respect to a plurality of individual substrates held on a carrier.
2. Related Art
An electronic component mounting system for manufacturing a component-mounted substrate by soldering and connecting electronic components on a substrate is configured by connecting a plurality of a solder printing apparatus, an electronic component mounter, a reflow apparatus, etc. In such an electronic component mounting system, inspection devices are disposed between respective apparatuses for the purpose of carrying out quality control at high reliability, and are given a function of automatically determining suitability of component mounting operations (For example, refer to Japanese Patent No. 3344739).
In the example shown by Japanese Patent No. 3344739 described above, in a component mounted substrate manufacturing system that is configured by connecting a plurality of operation portions such as a solder printing portion, a component mounting portion, a soldering portion, etc., inspection devices are disposed at respective portions to detect predetermined monitoring points. For example, a solder printing inspection device is disposed at the solder printing portion, which detects monitoring points of a printing state such as thin spots in soldering, positional deviation of printing, etc. And, where these detection points come out of a normal range and are in a warning range, operation control instructions to change the operation status and to correct the same are outputted to facilities positioned at the upstream and downstream sides. For example, where a printing position has deviated in a specified direction, an operation change instruction is outputted to the upstream printing device to correct the positional deviation, and an operation change instruction to correct the component mounting position corresponding to the positional deviation is outputted with respect to the downstream component mounting devices.
In recent years, small-sized mounted substrates have been widely used in line with downsizing of electronic apparatuses. In many cases, generally, component mounting work with respect to such small-sized mounted substrates is collectively carried out with respect to a plurality of substrates, and such a mode is adopted, in which a plurality of small-sized individual substrates are held on a carrier. However, if an inspection function of a conventional electronic component mounting line including the related art example described above is applied to a component mounting mode in which such a plurality of individual substrates are held on the carrier, the following problems are brought about.
That is, a plurality of individual substrates are not necessarily held in accurate positions set in advance in a carrier when holding these individual substrates on the carrier. Usually, the holding positions thereof become uneven in a specified range. Where a specified individual substrate greatly slips due to a certain cause in comparison with the other substrates and is in an abnormal state, if the printing position is corrected in a printing device using soldering position information obtained by the print inspection device as it is, incorrect data resulting from the abnormal state is brought in as feedback data. Resultantly, inappropriate correction data is fed back to the upstream side. Thus, in the conventional screen printing apparatus, there may be cases where appropriate printing position data cannot be fed back in a component mounting mode in which a plurality of individual substrates are held on the carrier.